Amplifying and detecting tube



1,644,796 w. n, 1927. H R STUART AMPLIFYING AND 'DETECTI NG TUBE Filed March 27, 1,926

INVENTOR my? P g's S aarzf.

%a1,fw. ATTORNEY Patented Get. It, 1927..

NMED

HENRY PAGE STUART F SEATTLE, WASHINGTON.

AMPLIFYING AND DETECTING TUBE.

a iimon filed March 27.11926, Qcrial m. 97,841.

This invention relates to amplifying and detecting tubes of the gaseous or vacuum three electrode type comprising a heating element insulatively mounted within a tubular cathode and having the usual grid or screen wires interposed between said cathode and a cylindrical or spherical plate or anode.

' Certain objects of the invention are to provide means whereby the heating element or filament and associated parts may be readily removed for renewal or repair without disturbing the vacuum or gaseous state of the device. Another object is to provide ventilation means whereby the heat generated by the filament or heating element may pass ofl and fresh air admitted. Other objects are to provide novel disposition and insulation of certain of the lead in wires whereby loss of current from discharges or corona efl'ects and other leakages is reduced to a minimum. Further objects are to provide certain novel means of support and attachment for the several electrodes together with other novel details of construction.

With the above and other objects in view which will appear as the description proceeds, the invention consists of the novel construction, adaptation, combination and arrangement of parts hereinafter described and claimed. These objects are accomplished by devices illustrated in the'accompanying drawings; wherein- Figure 1 is a view substantially in central vertical section of "a device embodying the features of the invention; Fig. 2 is a fragmentary View showing a portion of the upper insulator provided with a tubular projection for outward passage of warm air;

Fig. 3 is a bottom plan view showing a modified disposition of the poles; and

Fig. tis a view in front perspective showing a modified form of plate.

Referring to the drawings throughout which like reference numerals designate like parts, the numeral 1 indicates a glass bulb that may contain gas or be in a vacuum state. Dis osed in the upper portion of said bulb is a tu ular glass or porcelain insulator 2 provided at its lower end with aflanged collar 3 that fits down snugly over a tubular thoriated or oxide coated cathode 7 making an air tight connection therewith. Said cathode may be made of or contain any desired electron emitting substance.

The bulb 1 is provided with the usual inwardly projecting neck or I destal 1? and the lower end of cathode 7 iii y be provided with a flanged collar 22 to fit snugly over a pro ection on the upper end of said neck and crimped as at 42 and imbedded in said neck, or any other desired means may be used for forming an air tight connection at this point.

Theneck 17 and cathode 7 are hollowed by a space 33 extending upwardly to the collar 3. Said space also extends through the porcelain insulator 28 secured against the lower end of said neck and internally threaded at 37 to receive a plug 32 having a base flange '38. Said In '18 inte rall prov ded with an insulatoi' pijection' 31 ex tending upwardly within the space 33, and an insulator rod 53, imbedded in said plug and pro ection, extends upwardly to a conical cup 8 at the upper extremity of said space. Said cup is made of metal and may be screwed or pinned to saidinsulator rod as Adesiied.

po e5, extendiii downwardl throu h bulb 1 and insulator 2, has its lbwer ei id sharpenedto fit conical cup 8. It will be obvious that a tight connection between said pole and cup will be made by screwing upwardlyon plug 32, as by means of a screwdriver inserted in the slot 52 shown in Fig. 3.f Polet51is sealedithrough bulb 1 by means 0 amea ca 4 aced overani filled with .ce men l'. 43 u i pple 6 and wherein an insulator 46 is installed for passage of the pole. It will thus be seen that an a r tight condition prevails between the here nbefore described elementsas a whole within bulb 1 and the bulb shell, and the space therebetween, as designated by the numeral 34., may be either evacuated or filled with gas.

A heat unit 9 secured at its upper end to cup 8 1S coiled around rod 53 with its lower lead securely held by annular brackets a1 close to insulator projection 31 and passes through plug 32 to the socket contact E.

Said lower lead may be coiled around said may be used for holding said lead in wire in place. It will now be obvious that a continuous path is provided for the current be tween said lead-1n wire and socket contact to a chamber 36 E through heat unit 9. The heat generated by unit 9 is allowed to escape from space 33 by means of a small hole 49 extending through insulator 2 and through a smal tubular projection 55 which projects upwardly from said insulator through cap 4 to the open air. Cool air entersspace 33 by means of a small passage 48 through plug 32. The ventilation means thus effected will.

cool the heat unit, cathode etc., thus checking disintegration of these parts and keeping the tube cool as a whole for manipulation by hand and at the same time will allow passage of a suflicient quantity of electrons and provide a more even discharge of same with probably no change in, the rate of their flow. Y

The base of bulb 1 may be set in a moulded one piece base of insulating material, or

same may be set within a shell 27 by means of cement 4A and an annular projection 35 on said base together with a projectlon 4:5

on the interior of said shell serve as means for holding the parts together. Said shell is also provided with an annular pro ecting shoulder 29 that holds insulator 28 in place against an annular flange 30 formed by crimping or bending in the lower edge portion of said shell. The numeral 26 designates a pin whose projecting end retains the tube in place when turned into the slot of a socket of conventional design. A contact pole Cpassing' through insulator 28 is held thereon by collars 39 and 40. The lead 12 from said pole extends upwardly through neck717 and is attached to flange 22 of cathode The neck 17 is provided with an annular shoulder 25 that serves as a support for a band 23 secured at'24 to a leg 13 of plate20. Any desired number of such legs may be used for supports and are preferably an integral part of said plate. One of said legs,.

such as shown at 14, passes'downwardly between neck 17 and a lower portlon of bulb l through the base of said bulb and insulator 28 to the pole P thus serving as a feed lead for said plate.

Grid wires 11 are held in spaced relation substantially midway between cathode 7 and plate 20 by'a plurality of supports 10 havmg equi-distant notches upon ,which the wires are wound to form a grid screen. The

lower extremities 21 of said supports are imbedded in glass neck 17 with the exception of the one shown at 10 which leads to contact pole G through said neck and insulator 28 where said pole is held by collars 56.

In Fig. 3 of the drawings pole E is shown adjacent the periphery of insulator 28 instead of passin through base 38 of plug 32 as in Fig. 1. Here said pole is provided with an extension 50 and a set screw 51 holds said extension and base 38 together thus preventing'plug 32 from getting loose.

This arran ement adapts the device for use in connection with the conventional four contact socket, and... eliminates the center pole.

Referring to Fig. 1, as is Well known,

when heating element 9 is connected with the current source the "thoriatedor oxide coated cathode 7, that may be made of or. contain any desired electron emitting sub-' stance, will throw off electrons through the control grid 11 to be received by plate 20."

Thus the character of the current in the grid circuit 11 will reform or filter the electrons passing the wires or screen of the grid in the form or order tuned to in the grid circuit from exterior waves of broadcasting. The electrons will thus be caused to strike plate 20 in the order necessary to produce the frequency oscillations in the plate circuit being received in said grid circuit and when amplified will reproduce like variations upon the diaphragm of the phone.

The spherical form of plate shown as a modified form in Fig. 5 is considered very efficient in providing more-surface for electron reception and less chance of electron waste or escape. An opening is provided in both the top and bottom for the passage of'the insulators, leads and other parts.

Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is 1. An amplifying and detecting tube comprising an air tight bulb having a reentrant integral neck, an air tight electron emitting hollow cathode mounted on said neck, means for emitting warm air at the top and admitting cool air at the bottom of said cathode, a heating element 'insulatively mounted within said cathode, and means for removin said heating element.

2. An amplifying and detecting tube com prising an-air tight bulb having a reentrant integral neck, an air tight electron emitting hollow cathode mounted on said neck, a heating element insulatively mounted Within said,

being hollow throughout their lengths, a

detachable plug threadedly mounted in the bottom of said neck having an insulator projection thereon, an insulator rod imbedded in said projection extending upwardly into said cathode, a contact cup mounted on the top of said rod, a heating element coiled around said rod with one end attached to said cup, the other end of said element leading downwardly through said plug to a contact pole, the other pole sealed through the top of said bulb and cathode, the lower end of said pole adapted to form a snug contact with said cup, and Ventilation means for said cathode.

4. An amplifying and detecting tube comprising an air tight bulb having a reentrant neck, an air tight electron emitting hollow cathode mounted on said neck, an insulator rod having a heat unit wound thereabout inclosed in the cathode, the lower end of said rod mounted in an exteriorly removable threaded plug concentric with said neck, the lower pole of said unit passing exteriorly through said plug, the upper end of said unit secured to a conical metal cup mounted on the upper end of said rod, and an upper pole having a sharpened end adapted to make contact with said cup extending exteriorly ofsaid bulb at a point diametrically opposite the lower pole.

In witness whereof, I hereunto subscribe my name this 20th day of March A. D. 1926.

HENRY PAGE STUART. 

